Fletcher hawk



(No Model.)

P. HAWK.

APPLIANCE FOR ILLUSTRATING SPHERIGAL TRIGONOMETRY. No. 405,354. PatentedJune 18, 1889.

NITE

ATENT Fries.

FLETCHER HAWVK, OF LEBANON, OHIO.

SPECIFICATION forming part of Letter S Patent No. 405,354, dated June18, 1889. Application filed November 16, 1888. Serial No. 291,048-

(No model.)

f0 all whom it may concern:

Be it known that I, FLETCHER HAWK, a citizen of the United States,residing at Lebanon, in the county of \Varren and State of Ohio, haveinvented a new and useful Improvement in Trigonometrical Appliances, ofwhich the following is a specification.

My invention relates to a trigonometrieal appliance; and it consists ina certain novel construction and combination of devices, fully describedhereinafter in connection with the accompanying drawings andspecifically pointed out in the appended claims.

In the demonstration of principles and problems in sphericaltrigonometry and solid geometry it is desirable to have some tangibleobject by which the various forms and the relations between lines andplanes may be accurately illustrated, in order that pupils of feeble orsluggish imaginations may be enabled to comprehend readily the basalfacts in these branches of mathematics. It is therefore my object toprovide a device whereby plane and solid angles and triangles may beformed, so that the teacher before a class (or the pupil who is deprivedof class-room privileges) may readily and quickly elucidatesatisfactorily the foundation principles in the branches of instructionreferred to, and thus save much time which would otherwise necessarilybe occupied in explanation and study.

In order that my invention may be more fully understood and theadvantages thereof better appreciated, I have illustrated the same inthe accompanying drawings, wherein Figure 1 is a perspective View. Fig.2 is a vertical sectional view taken longitudinally of the slot in thedisk. Fig. 3 is a similar View with the half-disks in a diiferentposition.

Referring to'the drawings by letter,A designates a disk, which isprovided with a radial slot B, extending from the periphery to a pointslightly beyond the center of the disk, and at the inner and-outer endsof this slot are formed bearings O O, in which are mounted the ends ofthe shaft D. This shaft is provided with a longitudinal slot d, havingan enlargement d at its inner end, and in this slot is arranged thehalf-disk E, which is I provided at the center of its straight or innerside with the trunnion e, pivoted in the said enlargement d. It will beseen that the halfdisk E is capable of a rotary movement around theslotted shaft, whereby it may be caused to assume a position at anydesired angle to the plane of the disk A; and, further, the half-diskmay also be moved around its pivot in the enlargement (1', whereby itmay be caused to assume a position on either side of the disk A or maybe allowed to eX- tend through the slot 13, as shown in Fig. 1 of thedrawings.

In suitable aligned bearings, Which are arranged, respectively, in thetrunnion e and on one extremity the ends of the shaft F, provided With alongitudinal slot fiwhieh terminates a short distance from the inner endof the shaft. In this slot is mounted the half-disk G, and from itscenter is cut a semicircle g, concentric with the periphery of the disk,whereby all points on the semicircle are equidistant from the peripheryof the disk when measured on the radii of the latter, thus enabling thedisk to be arranged in any desired position in the slot or removedtherefrom e11- tirely.

Upon the disk and half -disks may be printed, impressed, or otherwiseindicated any desired system of notation, whereby any desired angles maybe formed between the disks.

By the proper manipulation of the parts of this device any principle orproblem in spherical trigonometry and many propositions in sphericalgeometry may be clearly and fully demonstrated and illustrated, wherebythe most obtuse pupil will be enabled to understand, and when the deviceis not in use it may be folded flat to occupy a small space, whereby itmay be carried in the pocket.

Having described my invention, I claim 1. In an educational appliance,the combination of the disk A, provided with a slot, and the half-diskmounted in the slot and adapted to assume a position at any desiredangle to the disk A, wherebyplane and spherical angles may beillustrated, substantially as specified.

2. As an educational appliance, the combination of the disk A, providedwith a slot B,

of the half-disk E, are mounted the half-disk E, mounted in the saidslot, and the half-disk G, swiveled to the edge of the half-disk E,substantially as specified.

3. In an educational appliance, the combination of the disk A, providedWith a radial slot B, the slotted shaft mounted at its ends in bearingsat the ends of said slots, the halfdisk E, arranged in the slot in saidshaft, and the half-disk G, swiveled to the edge of the half-disk E,substantially as specified.

l. In an educational appliance, the combination of the disk A, providedwith the radial slot B, the slotted shaft D, mounted in bearings in thesaid slot, the disk E, arranged in the slot and pivoted at its inneredge to the shaft, and the half-disk G, swiveled at its center to theedge of the disk E, substantially as specified.

5. In an educational appliance, the combination of the disk A, providedwith the slot B, the slotted shaft D, mounted in the slot, the half-diskE, arranged in the slot in the shaft, the slotted shaft F, mounted inbearings on the half-disk, and the half-disk G;ar-'

shaft, the shaft F, mounted in bearings on the edge of the half-disk End provided with a slot f, terminating a short distance from the innerend of the shaft, and the half-disk G, mounted in the said slot andhaving the semicircle 9 cut from its center, as and for the purposespecified. I

In testimony that I claim the foregoing as my own I have hereto affixedmy signature in presence of two Witnesses.

FLETCHER HAWK. WVitnesses:

ELLA HAWK, CAROLINE S. ADAMS.

